Going through my watched threads and having a ”tidy up”. In the end I bought a cheap, £20 iPhone off e bay. Downloaded a few speedo apps selected the one that had just a simple digit readout where you can change colour and units very simply. Works a treat, driver delighted with it. Interestingly Sat Nav & this show the same speed but approx. 3-4 mph slower than van speedo so we make allowances for this. Thanks for all the ideas and help. really suited.